Thoughts on the pathophysiology of nonallergic rhinitis.

Nonallergic noninfectious rhinitis is a diagnosis by exclusion, meaning that a number of poorly defined nasal conditions that have in common allergy and infection as a cause of the rhinitis have been excluded. The etiology of some subgroups of nonallergic noninfectious rhinitis, like nonallergic rhinitis with eosinophilia (NARES) and drug-induced rhinitis, are quite well defined, but in the majority of the patients, the etiology and pathophysiology are unknown. These patients are classified as idiopathic rhinitis patients. A careful determination of the intensity of the symptoms combined with modern diagnostic tools enables us to discriminate idiopathic rhinitis patients from normal controls. This review discusses the possible pathophysicologic mechanisms of nonallergic noninfectious rhinitis, with emphasis on idiopathic rhinitis.